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Journal of Coatings Technology and Research

, Volume 4, Issue 3, pp 311–315 | Cite as

Structure development in polyurethane networks based on star-like precursors

  • P. VlasakEmail author
  • M. Duskova-Smrckova
  • K. Dusek
Article

Abstract

A network formation from an OH-functional star oligomer and two isocyanates (HDI and HDI-trimer) was investigated by changes in the critical molar ratio of OH groups \((r_{\rm OH})_{\rm c}\) as a function of dilution. The critical ratio \((r_{\rm OH})_{\rm c}\) is such critical excess of OH groups at which the critical conversion of NCO at the gel point groups reaches 100%. The dilution effect was interpreted by pronounced cyclization, which was higher in the case of the HDI-trimer compared with the HDI.

Keywords

Polyurethane networks Gel formation Critical dilution Critical molar ratio Cyclization 

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Copyright information

© FSCT and OCCA 2007

Authors and Affiliations

  1. 1.SYNPO asPardubiceCzech Republic
  2. 2.Institute of Macromolecular ChemistryAcademy of Sciences of the Czech RepublicPragueCzech Republic
  3. 3.Faculty of Mathematics and PhysicsCharles UniversityPragueCzech Republic

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